Gunnery training



Aug. 27, 1946. F; wALLER ET AL GUNNERY TRAINING Filed Oct. 17, 1941 11 Sheets-Sheet 2 NTOR8 F R D WHLLEB 2 1946- IF. 'WALLEI ETAL 2,406,574

GUNNERY TRAINING Filed Oct. 17,- 1941 11 Sheets-Sheet s INVENTORS FEED WHLLEB w ROBE/PT 01255552 BY H. MflETYN lap/(5e ORNEYS .wm m w Aug. Z7, 1946 F. WALL-ER Em 2, 6, 74

GUNNERY TRAINING IMMWJ Q Aug. 27 .1946; F. WALLER ETALM 2,406,574 I GUNNERY TRAINING Filed 001;. 1'7, 1941 11 SheetsSheet 9 FkAWEMPS gar. a MM n 7 N e m E a m W w g- 1946. F. WALLER ETAL I 2,406,574

GUNNERY TRAINING Filed 001. 17, 1941 11 She ets-Sheet 1o Aug. 27, 1946. F. WALLER ET AL I v GUNNERY TRAINING 17, 1941 11' Sheets-Sheet 11 Filed Oct.

INVENTOR FRED WHLLEE 14- ROBERT BEES-SLR H. MARTY/V Bfl/(FB W 'ITORNEYS Patented Aug. 27,1946

GUNNERY TRAINING Fred Waller, Huntington, N. Y., and Willis Robert Dresser, Long Hill, and Henry Martyn Baker, Essex, Conn, assignors to The Vitarama Corporation, New York, N. .Y., a corporation of New York Application October 17, 1941, Serial No. 415,374

(ores-25) 52 Claims.

This invention relates to gunnery training and has for an object the provision of improvements in this art.

One of the objects of the invention is to provide training apparatus which in physical appearance, setting and mode of use corresponds in the greatest possible degree to actual service equipment, environment and use.

The invention may have a variety of uses, but as an aid 'to a rapid comprehension of its nature and advantages it will be described in connection with the training of machine gunners for shooting airplanes and other moving targets.

At present there is practically .no way to prop erly train an airplane gunner except in actual combat. He may shoot on a range to test his general aptitude. By this and other tests men may be selected for gunnery service, but they still need experience of actual conditions in order to acquire that instant and precise judgment of "distance, speed, windage, gravitational effects, time of bullet flight and other conditions, which is so necessary for .rapid and effective firing required in combat.

Practically the only attempt now made to provide service gunnery training is that of towing a sleeve or other target behind an airplane and permitting the gunner to shoot at it from another airplane. This at best is not very good practice because the lineally moving target is but a poor substitute for an airplane in combat acrobatics. Moreover, this requires the use of much expensive service equipment for training only one man at a time, and in addition there is danger of injury to the personnel or equipment, or to life and objects on the ground.

According to the present invention, motion pictures are taken from the viewpoint of a pros.- pective gunner, as of combat airplanes from another airplane. These pictures are subsequently projected from the same relative position upon a screen, and a gunnery trainee or student is placed with a dummy gun as near as. conveniently possible to the projection axis to aim and fire at selected objects in the pictures on the screen. There may be several guns for as many students grouped closely around the center of projection. No actual projectiles need be fired at the screen. Instead, control apparatus, is operated in accordance with the picture projection and gun position at the time of firing, which determines whether a "hit or miss is made and provides intelligence thereof. This control apparatus is preconditioned .to account for the position of the target in space,

its distance from the gun, the ti-me of flight "of "2 an imaginary projectile from the gun to a point of burst in the plane of the target, and other factors, to provide a very accurate control condition relative to or against which thegunner operates. If he matches these control conditions, the apparatus will register his shot as a hit.

The indication of a hit may be given in many dilferent ways. The necessary impulse having been provided, a great variety of indications may be possible, as "for example a bell, a light, a touch, a record mark, or the like. p

The apparatus may also be used for purely instructive purposes as, for example, to project 'a spot of light together with an image of the target on the screen to indicate where the burst should be, or to indicate the correct point of aim to make a hit, the trainee following this in his sights or later attempting to duplicate the situa- 'tio'n. v I

The general outlines of the invention have been noted and reference has been made to motion pictures taken and projected from a gunners viewpoint. A si'ngle filin will serve the invention; but for greater realism and more perfect training .a number of film records are made at different angles from the gunners position. When these films are projected in the same relationship upon .a concave curved screen, there is provided a realistic three-dimensional effect. And when to this there is added sound (which also may be recorded from the gunners position) frame number of sources distributed over the screen, the approach to realism is very striking. Such a system of projection with sound is disclosed in thetco-pending application" of Fred Waller and Ralph Walker, Serial No. 163,712. filed September 14., 1937, now Patent No. 2.280;;206, April 21, 1942. I

When this curved (commonly spherical) screen has a radius of about twenty feet or more, it provides a setting which substantially satisfies the conditions for correct visual judgment of distance'because, for the average person, the judgment of distance and perspective beyond about twenty feet is not dueto the interpupillary distance of the eyes, but is due to peripheral vision,

that is, what the eye'sees outside its central area of sharp focus, and also to relative movement perspective, and to color or atmospheric perspective. When a colored three-dimensional motion picture is projected on a screen of this size together with a three-dimensional reproduction of the sound record made at the gunners position, or its approximation, practically all the elech'ts of realism are faithfully reproduced.

When a trainee is placed near the projection center of such an environment and fires at a moving target, say a moving'airplane with its motors operating and its guns firing blanks, there is provided an opportunity to observe not only his judgment but also something of his psycho;- logical reaction under conditions which almost duplicate actual service conditions.

To this there may be added mechanism for reproducing the sound of firing the type of gun which isrepresented by the dummy gun; and the dummy gun may be vibrated when the trigger is pulled, to Simulate its normal vibration in use. Also the trainees mount may be similar to that in service and arranged to. have. movements which simulate to some extent those of an airplane in combat; and elements of surprise or shock may be provided to obtain the trainees reactions. These effects may be varied 'to suit different service requirements or the instructor's fancy. They are mentioned to illustrate how the invention can be carried forward to provide test conditions which are real stic and which almost wholly duplicate actual service condi? tions. I

The invention provides for obtaining a highly accurate test of the trainees gunnery ability and a great deal of precise gunnery practice for a large number of studentseat a relatively small expense, and this under conditions where immediate indications of results are given to the trainee or his instructor. This is in contrast to towed sleeve gunnery, mentioned above, where the sleeve can be examined for hits only after the flight 'is over, and to camera gunnery where the record must be developed, during which time the student has forgotten many of the conditions under which the record was made. Moreover, camera gunnery does not provide for time of flight, windage, gravity, airplane speeds and the like. 7 To merely sight directly on a moving target is to miss itcompl'etely under most service conditions, just as is true in skeet, trapshooting, bird shoot ng or the like. Incidentally, these sports may also be" effectively taught or be used as a source of amusement according to the present invention. V V

Having seen how a plurality of film bands and associated eifects maybe employed to obtain realism of environment, we may, for simplicity, return to the consideration of a single film band. Say atarget airplane is seen approaching in a certain sequence of pictures in this band. A projectile, more commonly a plurality of projectiles, as when a machine gun is used, is fired with sufficient lead toiarrive at a given point in space, taking account of time of fl ght, etc" when a given vulnerable part of the airplane arrives at the same point, and a hit is made; The airplane image at that time is located at a given position or coordinate point on a single picture or frame of the filmband. It also occupies a correspond ng coordinateposition on the projected picture area'on the screen. Ifa light spot were'left on the screen where the burst was placedyand if a small pin hole, cross or other transparent areawere made in the frame where the hit was to be made on the airplane, then when the airplane reached thesame place, the hole or-hit spot would exactly coincide with the burst spot. For the moment gravity drop, which would require the aim to be vertically displaced relative to the hit spot, and windage, which would require the aim to be horizontally displaced relative to the target, areneglect d.

reasons.

hereinafter.

Further, it is desired to utilize the hole or spot in a frame to control certain auxiliary apparatus Basically, therefore, the pin hole, cross, or other indicia hereinafter referred to, might be provided directly in each frame of the actual picture film band. Preferably, however, a separate band (or hands) which will be referred to as a control band, is usedinstead, for a number of For one thing, the picture filmmay have many natural light spots which might be confused with the hit spot, hence it is more dependable to use a control film band which is wholly opaque except for the purposely made control spots.

Further, if the hit spot were made in the picture band it would be projected On the screen and this would confuse or unduly guide the trainee.

be placed in the picture band, as explained and the full frame'of picture film is required for the projection beam at the moment of projection.

Further, it is desired to compute the distance fromthe gun to the target-which may be done 7 by known photographic triangulation methods which need not be described here-and set against it the time of flight of the projectiletaken from ballistic tables of the particular gun and ammunition, and other pertinent data-in order to properly place the spot on the band. It

can be seen that it would not fall at the spot on be done conveniently with the picture film because the target has not arrived at the point of the burst at this time. It is preferred to place thi indication on a separate control band which may be, in effect, displaced longitudinally relative to the picture band to take care of this situation.

Moreover, when a plurality of picture film bands are employed to project a mosaic of separate areas which form 'a composite picture on a large or spherical screen, the target may not remain on a single band while it is in the range of the gun. When a separate control bandis employed it may be proportioned to the total area of the screen or of all film bands or to the coordinate range of movement of the dummy gun, and

the indicia provided in suitable proportionate relationship on the control band to the locational coordinates of the target inthe picture.

In some instances it may be desired to form I the control band of metal or other durable material, though a sensitized band is still contemplated when prints are desired and where the weakenin effect of holes can be avoided by providing transparent spots. Also it may be desirable to use longer or wider frames to permit of greater distances and accuracy and to permit more equipment to be mounted about the control frame zone. For example, the frame of the control band may equal two picture frames in length. Or it may be desired to provide conventionalized indicia of the targetposition on the control band.

For certain instruction purposes it may For: usual service. requirements it will be sum cient to record the hit or; project an. image oi the burst spot on the screen, or both, when. the target arrives at itsgiven position. For certain; service it may be desirable to represent the burst on the screen as soon as; the gun is fired, and to preserve the. spots on the screen a: certain length of time, as by using a phosphorescent. coating on. the: screen. The last bursts will appear more brilliantly and fade or decay progressively so. as to gradually disappear.

For ,this. type of, spot projection. and: also for the delayed spot; projection itmay be. desirable toaprovide correction for; deviationsof theproj'ectile from straight line flight; to; .talrezaccdunt of windage; gravity drop, parallax; and. other variable factors". Preferably this is. done: by regulatiing. the. position; of the. spot projector from one or more controlbands which: have been. prepared to compensate for-these. displacements. One: con.- trol band maybe used for all purposes" but the last mentioned" factors may be accommodated by one or more control bands apart from the control band which; registers hits; and. projects the delayedburst' 'spotiafter. the: correct time of flight. This avoids undue. complications for beginners, yet requires advanced: students to take into account more; of. the factors of" actual service. In thisrway' special problems: may be taught. These iactorsmay or'may not: be. taken intoa account in preparing the control band. with aim spots for indicatin hits. If theyare, the sights may be required; to. be aimed higher or lower to compensate for gravity drop. and other factors which affect elevation; 01" with more or' less lead than that; required for time of flight of the projectile to compensate for windage, direction of approach,. speed of gunner-"s airplane, and other factors which affect train.

The enumerated and other objects; features and advantages of the invention: will appear from the. following description of certain embodiments: of the invention, reference being made to the accompanying drawings, wherein:

Fig. 1 is a schematic view of apparatus for furnishing immediate intelligence of correct aim o'r'hits I Fig; 2:is a schematic view (:whi'ch is to be regarded as: combined with Fig. 1) of apparatus for furnishing an indication of hit at the time they are: made, allowance for time of flight having beenmad'e;

" 3 is a schematic view (which is to be regarded' as combined with Figs. I and 2') of apparatus'. for automatically adjusting the delayed hit; or burst spot to take account of wi'ndage, gravity drop, advancing or receding target speeds, parallax and the like I "@Fig. 4a is a view of'a length of control film band usedin the apparatusshown in Fig. 1, the image of the target airplane being superimposed in I dotted lines to showiwhat its relationship to the aim-punch mark or' cross would be if the punch mark weremade "in the projection film hand (here assuming that 'one'and not several fll'm bands is: used torprojection, that a projection speed of sixteen frames per second is used, and that the target airplane ismovingparallel to the focal plane at a distance of one-half second time of'flight) i Fig. 5 is: a similar view with. apertures ofvariahl'e. size, ithere being: assumedthat: the airplane is moving straight. toward the gunner;

Fig. 6 is a. view of a. length of. controlfihn band used in the apparatus shown in Fig; 2- the image Fig. 9. is a view of one unit length or frame of control band when the functions of the apparatus of Figs. 1, 2 and 3 are combined;

Fig. 1021s an isometric view of the actual apparatus adjacent the control band of Fig. 7;

Fig. 11. is avertical sectional view of apparatus for proiecting the delayed hit spot when the gun itselt is left free for continuous aiming movement;

Fig. 12 is a. vertical section taken approximately on the line f2-l 2 o-fFig'. 11;

Fig. '13 is a front perspective view showing an exemplary arrangement when five projectors, a spherical screen and four dummy guns are used;

Fig. 14 isv an isometric view of part of the apparatus of Fig. 10 when a device for punching crossmarks in the film is substituted for part of the indicating apparatus;

Fig. 15 is a perspective View of apparatus for regulating aim accuracy as shown in Fig. 10 or for photographically making crosses of variable size as shown in Fig. 5;

Fig. 16 is a longitudinal section. through a part of Fig. 15; 1

Fig. 17 is a perspective View of apparatus for making the lag apertures shown in- Fig. 4; and

Fig. 18 is a view showing control apparatus operated by the equipment shown in Fig. 3 and the third zone of the control band shown in Fig. 9;

Referring first to Fig. I, a projector 20 is properly associated with a screen 2 I to project thereon a series of pictures from a picture film band 22 For a concave screen of double curvature, such as the spherical screen illustrated, a plurality of projectors may be used, as illustrated in Fig. 13, and as explained in the patent referred to above. Preferably the projectors are arranged behind the geometric center C (Fig. 13') and have their optical axes located on radii through the center C. The pictures aretaken by cameras arranged in approximately the same way at the gunners position, preferably in actual mock combat conditions; In Fig. 13 five projectors are. shown but the number may be varied.

All of" the projectors are run in synchroni'sm and the film bands are started and run together just as the pictures were taken by synchronized cameras. Perfect synchronization may be reali-zed in many different ways, mechanical drive and-connections being employed in the apparatus used; but it is not necessary to explain the wellhorizontal aXisc'The shatts; 26 are mountedin a permit the gun to move in train in horizontal planes about a vertical axis.

The gun, thusmounted, has coordinate movement,.which may be limited in any suitable man- 7 ner'to confine its range to the area of the screen or any desired portion thereof. The gun is provided with sights 33 of any suitable type to permit the gunner to aim at the proper point relative to the target. A trigger, 3| may be employed to control a switch 32 to initiate the actionof the control mechanism. Closing the trigger switch isreferred to as firing the gun,

A number of sound reproducing devices S are provided at various places about the screen .to re-' position or, itmay be, artificial sounds'which are appropriately prepared. Several synchronized phonographs, sound tracks on several films, several sound tracks on a single phonograph record, several sound tracks on aseparate sound film band of a synchronized projector, an arbitrary selected sound of any type, or any other desired sound-accompaniment may be provided b known practices. I

The coordinate movements of the gun in elevation and train are transmitted by suitable cone nections to a control mount or support 35 which has corresponding coordinate movements. Whereas the amplitude of movementof the gun sights may be enough to cover the area on the screen, the amplitude of the mount 35 or such motion receiving means as may be provided is limited to the size of a frame or control indicia zone of the control band 36 which at any given time is stopped in front of the mount. As stated, this band 36 may be the picture fihn band, or a band of the same or a different size or character which is run in synchronism and step with the picture film band or bands, or an optical enlargement of any portion of any of these bands. v Any desired mechanism may be employed for transmitting the coordinate ,movement of the gun to the mount 35. As illustrated, a pair of equalized cords, cables, bands or chains 39 transmits the movementin elevation and a similar pair of members 40 transmits the movement in train. Changes of direction'are accommodated by pulleys 4| or the equivalent. i

In Fig. 1 it is merely indicated by arrows there.- on that the mount 35 has coordinate movement,

but in Fig. 10 the actual mounting on coordinate slides is shown and will be explained later.

The control band 36 is carried by reels 41, 48 and is fed downward by the intermittent drive mechanism 49 powered by a Geneva shaft .59 from a motor M through a sprocket chain The motor shaft 52, through a sprocket chain 53, drives'the mechanism of the projector 23. By this-or equivalent mechanism, drive synchronism between the picture film band 22 andthe control band 36 is accurately maintained at all'times. 1

Means are provided for furnishing an immediate indication of a hit if made. opaque control band 36 is provided with light apertures 55, here formed in the shape of a cross. These apertures occupy a definite coordinate position for each frame of the band which is halted at .the control gate. A light beam is passed through this aperture to reach a light sensitive element such as a photo-electric cell 56 in order to initiate the indication of a hit or correct aim.

The lightbeam may be produced by a lamp 51,

a collimating lens 58 and a conical mask 59 have As stated, the

8 'ing a similarcross-shaped aperture 60 which is' positioned very close to the control band. The lamp, lens and mask may all be mounted on the movable control mount or support 35, and, if desired, the'light sensitive element or cell may also 'be mounted thereon. However, as shown in Fig. 10, it may be satisfactory to mount the element carrying the aperture alone on the movable support, the projected beam and light receptive cell having enough latitude to cover the movement of the aperture. The energizing connections 6| of the lamp and the'leads 62 from the cell 56, if mounted on the support,

will be of such a nature as to furnish no resistance to its 'free movement; c

.It will nowbe clear that when the conical mask has been properly positioned by the coordinate movements of the-support 35 due to movements of the gun 25, ,the'aperturefillin the mask will coincide with the aperture 55 in the frame which is halted in frontof it and the light beam will reach the cell 56 to cause the indication of a hit or correct aim to be registered. This may be evidenced by a bell 65 through a control box 56.

In order to guard against giving an indication while the control band 36 is moving, any suitable interrupting means may be' provided, such as a light, shutter, switch, or the like. In Fig. 1 a switch is shown for simplicity, this here comprising a rotating contact bar 61, fast on an in sulating ring on' the motor shaft 52, which is adapted to connect a pair of contacts 68 to complete the ready circuit of the cell 56. The

trigger switch 32 is held closed for the instant Inasmuch as the aperture cross 55 in the con- .trol band provides an'immediate indication of a hit when the gun sights 30 have been aimed at a point or burst spot in space which will be reached by the projectile and the target after the time'of flight, it will be seen that if the cross were actually placed in the projection picture film band it would not coincide with the image of the target on that frame. It will be where the target is shown on a later framelater by the time of flight of the bullet. Fig, 4 illustrates this situation. Here the target 15, shown in dotted lines, reaches the position of the. cross eight frames after the shot was fired. This will be noted by following the vertical coordinate of the aperture cross 55 in the lower frame Fl upward to the eighth frame F8. 7 The control band moves downward as it does in the illustrated apparatus,

as shown by the arrow alongside. The plane .or target, of course, has moved forward an equal amount by this time, it having for simplicity been assumed to rnOVe p aral1el-. t0 the picture plane g and to have remainedgat adistance of 4/2 second away. The distance o or /2 secondti'mewof flight is knownfand the common photographic ,Asimple and convenient-method of placing the hitoraim crosses is to assume that a hit has been madeand then in theory to move the target back on its path and to move .the projectile :back into the .gun until the time of flight period is consumed. Having determined the, time of flight, this could readily be .done .on 'the picture film by projecting a hit cross :beam exactly on the target, holding'it in this position, moving the pic? ture film backward the number of frames it moved during this time, and then punching a hole in the frame which then appeared. yThis is the plan employed for punching, except that when a control film band is employed to take the hit crosses, the picture film is kept stationary and the control film band is moved backward the required number of frames and then punched. When the, control {band is moved forward again to a starting point which is even withtheastarting point of the picture film, as is done for pro- J'ection, it can beseen that the hit crosses will have the proper position and lead to indicate hits or correct aim assoon'as the trigger is pulled.

This procedure is followed for each frame of any sequence of pictures or frames in which the target isin or near the range ofthe gun or vision, the picture film being moved one frame at a time and each frame of the control band being fcorrespondingly set by reference to a prepared tab,- ulation,and marked with the hit crosses; .Frame counters may be associated respectively with the moving means of the two bands to show their relative positions from matching zero starting positions at all times,a connecting drive with, a clutch or a differential coupling being employed to keep them in step. Such counters are indicated in Fig. l at 80 and 8| and a differential by the numeral 82. If desired, a counter may be provided on the differential to indicate directly the displacement in number of frames between the two bands. Y Y

This presumes that the aim registering indicia are located on crossing coordinates like the target, and that the projection apparatus may be used for preparing the control band. And this may be done, as shown inFig. 10, where the light beam projection equipment on the movable support 35 may be used to produce a photographic exposure on sensitized film :or where, as shown in Fig. 14, a film punching device P is substituted for the beam control equipment. When a picture frame is;projected to throw the target image on the screen (heat insulating shutters being provided to prevent injury to the film) and the gun is sighted on the target, the beam or punch is in the position which the aperture 60 will occupy in projection if the aim is correct, and the band may be provided with the hit or aim registering cross 55 in exactly the right position. The control band will, of course, have been properly positionedrelative to the film band for providing each frame with a hit cross at the proper lead in accordance with the tabulation of computations which ha been prepared for each frame of thisparticular sequence. ,If the target is approaching and the time of flight decreases, say from 8A6 to 1 5' second, one frame will be markedlike the one preceding to maintain proper coordination. If the target is receding and the time of flight increases, say from 15 to 1%? second, and two aperture crosses are figured for a single frame, they will not be so placed; instead, only one aperture cross will be made.

The use of the apparatus shown in Fig. 1 will be readily understood. The gunner, by his sights or what is known *ashfhosefiring.

with the aim spot.

, If the rear sight 3!),is 'a:lamp and .the front sight is a collimatin'g lens, a sharp beam of light may be directed on the screen as the sight spot. This'may .be the regularsighting arrangement for an individual gun .andeach of several guns may have a different colored light spot. structor 1-m'ay'operate' switches vto throw :a beam whenever he desires todetermine where the gunner is aiming. It is particularly useful for an instructor to have such an .aim spot light avail-- able when he wishes to stop the rapid projece tion-and illustrate the correct aim, frame by frame. This he may readily do by moving the gun, with the trigger and commutator switches closed, until an alarm is given. Anassistant may aid in rapidly aiming the gun .forreXact registry by watching the position of the cross in the mask (Fig. 1-0) relative :to the cross in the control band. If he then wishes to show the distance to the target he can leave the gun pointed and turn the picture film forward, counting frames as he turns, until the target coincides This gives students good judgment of distance, timing and aim forany particular type of aircraft or anyother target.

The screen may be coated with phosphorescent material and a suitable light beam used to leave a track of the aim light spot on the screen which may be followed with reference to the projected image of thetarget. If the spot beam is interrupted periodically it will leave aseries of spaced spots which progressively fade out. This is readily done by connecting the aim lamp into the trigger switch circuit.

When the control band is provided with the light apertures it may be convenient to form all of them by a device of unchanging .size, in which case they will all be the same size, as

shown in Fig. 4. This, however, does not necessarily agree with theactual situation or most preferred practice. It maybe desirable to provide hit apertures of different or variable size. For example, if the: airplane is approaching, the

target area in which a vital hit may be :made

increases in size, as shown at 55' in Fig. 5. Itis desirable to take this into consideration, and this may be done by providing apertures of increasing size. It may also be desirable to diminish the accuracy required of beginners, and this maybe done by making all ofthe apertures in the control band larger or by increasing control band, there will not be enough light transmitted to energize the photo-electric cell and furnish an indication or alarm. If there is a partial lack of correspondence in either coordinate axis, the indication will not be given.

The iniing-in-this respect. form maybe used. Several of these are shown 7 l I It will be realized that a cross is .very 'discri'min'at But a y suitable outline in-Fig. .8. Here are shown ahollow. circle or annulus, a hollow circle with an enclosed hollow punches, but byphotographic or beamregulating fmeans it isrelative'ly easyi In the latter case'the aimregisteringaperture isnot an actual hole intheband but a transparent spot or pattern-.in an otherwise opaquesframe Thismakes duplication easy. and -leaves the band stronger. than if-it were punched. i i

i A simple method of making" variable crosses is to pass the exposure beam through an expan-' sible cross-shaped diaphragm 81 similar to a collet chuck, as shown in Figshlii and 16. Here-four tapered spreading elements 85 are opened or closed by. a=tapered sleeve 85 which by turning ismovedupor down the taper. r The size maychange, as shown in Fig. 5, to correspond-to the apparent size of an advanca 1115.01. receding target; or all crosses may be made ofthe same size,-the size depending on the degree-f accuracy required.

As shown in Fig. 10,- the mask cross in the pro jector may be similarly forrned by an expansible' collet 81 to vary the area through which the light can reachthe aim registering. or hit aperture. This will affect the-required accuracy considerably, even when the sizeof the aperture crosses'in'the band is notchanged. For a'relatively stable condition; similar results may be obtained by varying the intensity of the projec tion beam or the sensitivity of the receptive equipment. ,But forvariatlc conditions the variable apertures in thecontrol band are most con venient. I r

i In Fig. there is also shown one-embodiment of apparatus associated with the control band gate, Here the control support is shown to be mounted in the guides of a second slide 89 which moves upon vertical retaining guides of a'.

fixed member 96. The cables 39 for elevation and the cables 49 for train are also indicated. Amplitude changing arms 9| may be provided; these having suitable links BIA connecting them to-the slides. It will be seen that an annular rotating shutter 92 is here used instead of a commutator switch shown in" Fig. '1, but the,

principle of interruption of the light beam except when the frame is halted at. the gate is the same in both cases. A

tion of a hit' when 'made, or,'it may be, the

striking point of a projectile or a burst or explosionin the plane of the target whether a hit been-made or not.

This apparatus accommodates the time lag or delay required for the time of flight of'the bullet, hence continuous or hose firing which was previously described is replaced by periodic firing in which the burst spot projecting mechanism is locked 'in position'from the time of firing until the hit is or should have been made r I Hefe, as before we find the' projector '20, screen Having; considered the apparatus for furnish CAD Cir

motor M, motor shaft-52, Sprocket chains SI. and

53, .ex'citer lamp .515, collimating lens 58, photo electric cell" 56, energizing connections .6 I of the eX'citer-lamp and leads 62'.from cell 56' toicon- 'trol box 66'. Y.

addition, the gun is provided with means for directing a beam of light to forma burst .spot 95-lonithe screen.v Such means may comprise a lamp 9$ and. a lens 91. Forsimplicity these means. are shown in Fig. '2 as being mounted directlyinthefgun, whereas preferably they are mounted on a support which is movable relative toithe gun; as shown FigsQll-and 12.:

- Inasmuch'as the burst spot proje'ctor 25 is to be left in a'fixed position relative to the screen from the time the trigger is pulled until the burst-appears; the bu'rstspot projecting means will belocked in position'during the time of flight of the bullet or for-any such time as might be desired. Or, as-shown, the spot may be projected at the time the hit is made and left for such additional timeas desired;

' The means for locking the support for the spot projecting means (here shown as being the gun) in position comprises brakes associated with the gun shafts. -The horizontal shaft 26 is providedwith a brake band I00, connectedto a toggle IOI a solenoid I02 acting when energized to tighten the brake band and a spring I03 tending constantly to release thebrake bandr- By leads I04 the'solenoid I02 is connected intoa power circuit to'be energized when the trigger switch 32 isl'closedQ This brake mechanism is mountedon the support 21. 7 I 7 Similarly the vertical shaft 28 is provided with a brake band III), a toggle III, a solenoid II2, a spring -I I3, and leads I I4 for energizing the solenoid when the trigger switch is closed.

- By any suitable lock circuit, including the leads II5'to the control box 66', the solenoids may be held in braking position for any desired period and then released.

Means are provided fortiming the period of projectile flight after the shot is fired. 'This period is correctly provided for on each, frame in any sequence, hence is also associated with the control band 36-or a separate control band if desired. Such a separate a band is shown in Fig. 6, and a composite band with two indicia 1s shown in Fig. '7.

'This control band 36, Figs. 2, 6 and 7, is provided with light apertures I20 for each frame, the apertures, as before, being either punched or made photographically. They may be rectangular instead of cross-shaped, as were-the aper tures 55. Instead of bein located on two coordinates in a given frame area, as were the crosses 55 shown in Figs. 4 and 5, the apertures I20 are a l located in a single transverse band outsidethat area. They: are disposed at different distances from a'given'marginal' line near one edge of'the control band, and this distance determines the'period of delay between fire and burst, that is, the time of flight.

It may be assumed, in approximate relationship to actual conditions; that the longest effective shot may be taken to have'a time of flight of 1 second or 16 frames of motionof the'picture andcontrol bands. A given transverse distance across the control band may then repre-f QATOBJWZL sent .l lsecond, and when this distance is divided into sixteenv parts, :each part represents a period of of a second. v I

A scanning plate I2I, provided with a light aperture I22 is arranged to travel at a predeterminedspeed across the control band. For a simple "case its speed may be taken as constant. Its speed Lmay besuch, for example, that its aperture traverses the horizontal band in which the apertures I29 are formed in one second, and when the aperture I22 coincides with the aperture I20 for any particular frame, a portion of the light beam from the lamp '51 andlens 58 passes throughto the photo-electric cell 5.5 and initiates the action of the control apparatus in the control box 6 6'. This willcontrol -the circuit 123 of the burst spot projectin lamp 95, the .solenoid lock circuit H5, and any other desired circuits. Means in the control box 66, or the relative sizes of the apertures I20 and I22, may determine how long the burst spot 95 will be maintained after the burst indication is initiated.

i .Means are provided for'actuating the scanner plate I2I in the desired manner. Such means may, as shown, comprise a spring I24 tending to hold the .plate in one direction and a cord or cable I25 adapted to move the plate at times at a constant rate in the other direction. The plate moves easily along horizontal guides shown in Fig. 10.

The cord I 25 is'wound on a'drum I25 secured to a magnetic or friction drive disk I27, which is placed near mating disk I28 of a constant speed drive motor MI, which rotates continuously. The drum I26 and its drive disk I2; are free to rotate and move vertically in fixed bearingsfor their shaft I29. .Normally they are held up by a spring I35 but are moved downwardto bring the disks I21, I28 into positive'd riving engagement by a solenoid I3 I whenthe trigger sv'ritch;32.is closed. The circuit I32 of'the solenoid is controlled jointly by the trigger switch 1 and the lock circuit I I from the control box Gfiflwhereby the solenoid, once energized 'by the triggertswitch, is maintained in action until'the scanner aperture I22 coincides with an aperture I20. to provide the delayed burst indication, and for "as much longer as may be provided for.

Thecon'trol of the scanner movements as well as other actions or indication may be assisted by limit circuits associated with the scanner, these including limit contacts I35 and 135 (which may be adjustable if desired), .a lead I31 to the scanner plate, and leads I38 and I39 to the contacts 135 and I36 respectively. The leads may be connected throughthe contro1 box 66 for the desired actions.

In the operation of the burst projecting apparatus of Fig. 2, the gun or light'spot projectinglmeans is locked up the .moment the trigger switch 32 is closed. The scanner plate I 2I is also started moving across the control band at constant speed. When the scanner has travelled across until its aperture I22 coincides with the aperture I529 in the control band, the burst indication is given. This may be the energization of the leads I23 oil-the lamp 95 to project a burst spot 95 on the screen. After the predetermined lapse of time the lamp is de-energized and the spot projector or gun-is taken from under the locking action of the brake solenoids I02 and H2. The aiming and firing actions'may then be repeated. l 7 7 Usually it will be desirable to leave the gun free lfor following-the target at all-times'. To

. -Tl leremay be a plurality; of

14 provide tor this, :as shown in 'Figs ll l and I2, the spot :proiector support 1 12 is mounted adjacent, andsin this :case within,the-=gun 25. The spot projecting lamp 915 and lens SIare mounted on this support and the gunlhas .an end opening large enough to permit the relative angular movementwithou t obstructing-the spot. The essential of the gun is its sighta -h'ence i ts physmar-ccnstruction otherwise may be varied as much :as desired 'i I The hori-zorital shaft -brake -=I 00 andi-ts-solencid I 92 are now-mounted on the support for -2-1N and the vertical shaft brake I-I'Il and its solenoid I I-Lare mounted on-apar-t'2 5'A which is position. -Opposed springs I'43 or'othe-r suitable means cause the spot projector to return to "a normal vertical position relative to the gun, and another pairv ofopposed springs IM or other suitable means causes the support-to return-to- :a normal horizontal position-relativeto the gun when released from the brakes.

and scanners associated, with up the practice.

onegun to speed In Fig. 6 a lengthoi control band SB'W iththe apertures-I20 is shown. The time of flight, as before, is assumed to be /2 or second and to remain constant because a situation has-"been assumed in which the target airplane flies par allel to the focal plane and remains at one given range. Therefiore, since the width-in the range across the'band is taken as representing "one sec-.

halted, a-switch 61', 63' (Fig.2) or the equivalent in a shutter 92' (Fig. 10) maybe providedas before. The method of forming the apertures I2'Il-is very simple. Having made a tabulation of time of 'il'ight foreach sequence of picture frames, the

corresponding 'framecf the control band is punched, or otherwise provided with the transparent area at the proper distance fromfthe initial edge'of the horizontalzone allotted for such apertures. The aperture I '20 may'conveniently be punched by the apparatus shown in Fig. 17. Herefthe band' 36' is led by a sprocket I45 provided wane;

frame counter {45. A punch M1 is carried by a slide I48 and to the slide I48--there is secured "a proportional lever I49 which moves over an enlarged scale 159. In this case the scale is divided in' to sixteen parts Within the range of movement of the lever "I49. This apparatus increases accuracy of location of the punch and keeps account of the frames being punched. If desired, the punch may be'replaced'by photographic means as in Figs. 1-0 and 14 for the aim registering apertures. For simplicity of description it has largely been assumed that the target was near and that the projectile travelled a straight line, in which case the burst-spot would coincide with the point of aim-inthe gun sights. For some-types of burst projectors training practice, greater refinement for closer duplication of actual conditions may be, required. The drop of the projectile due to gravity and the lead or lag due to windage when firing from the side of aspeeding airplane and other factors may need to be taken into consideration.

' This may be done simplyand easily with they equipment already described by plotting .and placing the aim registeringapertures in accordance with the existing conditions. When the ravity drop is l tedit wil be necessary f r the gunneri to aim above the targettozscore a hit.

The burst spot will thenincorrectly be located above the image. of the target on the Screen.

Similarly when windage is plotted it will be nee-1 essary to train the gun sights aheador behind the normal straight line flight position in order to score a hit. The burst spot in this case will For more frequent indications or tracers, a light spot may be more frequently projected to leave a {track} of closely'spaced spots on the screen. In

the latter case, neithenthe gun nor the spot projector will be locked up.

In order to place the spot relative to the target to take account of various factors, there; may beprovided the compensating or deviation cont o pp a us shownin Fi I Here, again, we find the picture projector 20, screen '2 I, ,picture'film band '22, dummy gun 25, its horizontal shafts 26, its support 21, its vertical shaft 28, its sights (onlyone is shownbecause parts are broken away), trigger 3|, trigger switch 32, control film band 36, supply reel I'L'take-up reel 48, intermittent 49, Geneva shaft 50, drive motorM, motor shaft 52, sprocket chains SI and 53, exciter lamp 51, collimating lens 58", a plu rality of beam concentrating lenses 58A, a plu- 4 rality of corresponding photo-electric cells 56", 1 V energizingconnections6|? of the exciter lamp,

and leads 62" from the cells 56" to the control box 662'. 'Leads I23 extend; from the control bex'ee'g r the spot'lamp as", the circuitincluding the trigger switch 32 and the. commutator switch 61'', 6 8.

. The control band 36 is here provided with a plurality of light aperture areas I55 for each frame, which register with/apertures I56 in a fixed plate I51.; The size of the control apertures I 55 may determine the amount of light reaching the light cells 55" and the strength of their impulses. Instead of relying upon the relative strength of a single cell it may be desirable to use a variable number of cells with a variable number ofapertures in an assigned zone in the control band foreach effect. The latter arrangement may employ a progressive relay action similar to that known in telephone dialing systems form is'selected for illustrative purposes. V

The spot projector camp 96 and lens 91") is miss d 9 a su rqr mitlvyhmn s. m va e or tracersp the apparatus described in connection with Fig. 2,. which accounts for time of flight, may be used.

As before, a light shutter, may I be used instead of the commutator switch, the I latter being shown for simplicity of illustration in and remote control of radio tuning. The simple I bOX.

In the operation of the. apparatus shown in onahorizontal shaft 26",ona shaft support 21',"

which in turn is carried on a vertical shaft 28! mounted on the gun.

The horizontal shaft 26" is provided with an arm 26A which is pulled upward with a constant force by a spring 26B and pulled downward with a;variable force by the solenoid 26C. Leads I60 extend from the solenoid 26C to the control box The vertical shaft 28". is provided with an arm 28Aiwhich may be operated as described above or pulled in one direction with a constant force by a spring 28B and in the opposite direction with a variable force by a solenoid 280; A mating spring 28D opposes the spring 28B and if no other forces are applied the springs maintain the arm 28A in a central position; A solenoid 28E when energized pulls the arm 28A with a a variable force against the constant force of the spring 28D. Leads I6I extend from the solenoid 28C to the control box, 66" and, similarly, leads I62 extend from the solenoid 28E to the control Fig. 3, the strength of light impulses trans mitted by the cells 56" will determine the amount of pull on the solenoids 26C, '2 8C and 28E and the amount of deviation of the spot beam. When a progressive relay action is employed, the number of light impulses transmitted will'then determine the amount of deviation of the spot beam. The action is continuous from frame to frame or maintained until changed, hence the deviation is maintained or varied without'permitting the spot projector'support to return'to the central or zero position except when it is authorized to do so.

When-the control band of Fig. 9'is used, one

transverse control ,zoneflis provided withaplue rality of aperture areas I55. These are in additionto the aim registering apertures 55 in one controlzone and the lag apertures I20 in another control band, and the apparatus shown in Fig. 10

for two zones together with" the showing of Fig. 3 will readily indicate how apparatus for more than two zones may be built.

The apertures I55 each have a fixed position for a given function and each, when present onany frame, registers with a corresponding aperture I56 in aperture plate I51. Positions for six apertures are illustrated in Fig. 9, but for simplicity only three apertures are shown in Fig. 3.

The legends on Fig. 9 indicate how these con trols are employed where their action is cumulative. The legend 1 right means that a ratchet allotted to move a ratchet disk to the right will operate once tomove the disk one unit space. The disk'is held in any given position by any suitable-means as, for example, by light detent or by friction fneans, and this holding force is relieved by any suitable means such as by a magnet actuated by the all clear aperture to permit the disk to return to a given zero position, as by the influence of a spring or springs. Similarly the 1 left aperture would cause thedisk to move one space to the left from whatever posi- 17 as; ju t described. The ratchet; disk is represented by the numeral HQ. The disk in assembly is: shown in Figs. 11 and 12., A similar disk I'1'I for vertical movement is also shown in Figs. 11 and 12. Magnet I12, when energized, moves the disk one: space to the right and magnet I13 moves. it one space tov the left. A magnet I14 may; be employed to release the detent when an all clear" aperture in the control band comes into its corresponding light beam at the aperture plate. A spring or springs I15 or other suitable means may be employed for bringing the disk to a given zero position when released from the .detent. The ratchet mechanisms will, of course, move clear of the disk after each actuation.

The ratchet disk "I, shown in Figs. 11 and 12, may be. similarly controlled by the f1 up, 1 down and all clear apertures of the control band.

An unused space designated as reserve is shown in the third zone I55 in Fig. 9, but this may be employed for any desired effect or influence. It will also be understood that a different number of aperture spacesmay be allocated as desired. That illustrated is merely representative for the present equipment.

The method and apparatus just described permit the gun to be aimed off the target and the action. This use is particularly valuable for inr struction; whereas the normal operation is more suitable for practice.

It has been explained how the punching device of- Fig. 14 may be substituted for the light diaphragm device 81 on the coordinately moving plate in the Fig. 10 assembly. For easy operation to avoid moving the punch P out of its correct position when punching the film band, the movable portion I18 of a bellows device I19 may carry the punch P and the bellows may be operated by a fluid compression bulb I80, a flexible tube I8 I connecting the bulb to the bellows.

The mechanism shown in Figs. 11 and 12 is capable of performing several functions. It has been partially described but it will be helpful to summarize the description and explain the details. It combines the locking functions of Fig. 2 with the spot influencing functions of Fig. 3, and, of course, the gun may be aimed and will move the slide as in Fig. 1.

It can be seen how the gun 25 is mounted on horizontal shafts 26 carried. by a fork support 21' which is attached to a vertical shaft 28. The cables for transmitting horizontal movement to the control mount or slide 35 are secured to a grooved pulley 40A fast on the shaft 28. The cables 39 for transmitting vertical movement to the'control mount or slide 35 are secured to a grooved pulley 39A fast on the gun concentric with the shaft 26.

In this arrangement the shaft 28 is hollow and the cables '39 pass through it to the pulley 39A which is within the gun. This makes a neat and convenient disposition of the cables andavoids entanglement with related parts.

The fixed support 25A is disposed within the gun 25, being carried on a bent neck I84 which passes through an enlarged elongated arcuate opening I85 or a notch in the bottom of the gun which permits ample turning and tilting movements of the gun. The bent neck I8! is secured to a fixed pedestal I86 surrounding and support ing the shaft 28.

Instead of mounting the-spot projector (96, 91) directly in the gun, as in Fig. 2, or mounting the projector support ("I2") directly in the gun, as in Fig. 3, the spot projector support I42 is so mounted in Figs. 11 and 12 as to combine the functions of the other illustrations, it being again noted that while the forms of Figs. 2 and 3' may have independent uses they may be regarded as parts. of the comprehensive system.

Referring backto Figs. 11 and 12, the spot projector' support I42 is provided wih aligned horizontal shafts 26M which are mounted in a yoke or fork; 2 1M having a' vertical shaft 28M.

The shaft 28" is turnably mounted in an intermediate support I89 provided with aligned horizontal shafts 26N which are mounted in a yoke or fork Z'EN having a vertical shaft 28N turnably mounted in the fixed support 25A.

The mechanisms of-Fig. 18 for moving the spot projector support I 42 relative to the yoke 21M and. for moving the yoke 21M relative to the intermediate supportIBQ and returning both' to.

zero positions are indicated in Figs. 11, and 12. Likewise the mechanisms similar to those of Fig. 2 for locking the intermediate support I89 to the yoke 21N and locking the yoke 2 1N relative to the fixed support 25A are indicated in Figs. 11 and 12. This arrangement permits the gun to continue aiming movements while the spot projector is held in position until the target image 'moves toward the burst spot.

Normally this intermediate support has a fixed or zero position relative to the gun, and when it is released from the fixed support 25A it is .returned to its zero position by springs I43 and I44, as previously described. When the intermediate support occupies a zero position, the spot projector is influenced relative to the gun just as it would be in Fig. 3, and it may maintain the adjusted position relative to the intermediate support when that is locked in position. And it may stillmaintain its adjusted position after the intermediate support is returned to its zero position relative to the gun. The spot may be continuously projected, as when a phosphorescent screen is employed, or it may be delayed, as disclosed in connection with Fig. 2', or it may be projected at any time at the will of the operator or an instructor.

It will now be seen that the invention provides simple and effective apparatus for instructing and training gunners. And While certain embodiments have been specifically illustrated and described, it is to be understood that the invention may'have various embodiments within the limits of the prior art and the scope of the suband the features of the target image, and means. influenced jointly by said position means and 

